Recent advances have been made in the use of differentiating agents in the treatment of certain cancers. These agents have been used both as adjuncts to traditional chemotherapy and as inducers of terminal differentiation. Although the most promising results have been in the field of leukemia research, progress is also being made with certain solid tumors. Our aims have been to examine the effect of certain differentiating agents on cultured glioma cells, to determine the interaction of these agents with standard chemotherapeutic agents, and to better characterize the "differentiated" state induced by these agents.